nightlight wrote: > i have been trying to output a digital value using parallel port. i > know there are two ways to do that. one is to use visa and the other > is portin and portout function. The labview version i am using is 6.i > student edition, so it doesn't support portout with the accessHW > function. therefore i am left with only visa. i have some difficulty > in getting it work. i grounded pin 11 and pin 12, and tried to use a > multimeter to measure the voltage between the one of the data lines > and ground. i thought when i ran the program and adjust the value that > i output to the port, the value i read from the multimeter should > change between 0v and about 5v according to the value i give. but i > never changed, always stayed at 3.3v. could anybody tell me the > possible reasons?
Well, I guess the student edition does not have support for the Call Library Node, does it? Otherwise you could go to http://cvs.sourceforge.net/viewcvs.py/opengtoolkit/portIO/ where you will find the files to do what the accessHW library is supposed to do. It works for me for NT4, W2K and XP, but I haven't tested it on W9x although it should work there too. That about the logic levels of the parallel port: don't expect to good voltages on a notebook computer and even desktops do have some problems. 0.8 V for logic 0 is sometimes already quite low and 3.3V for logic one can also often be the max you can expect. Rolf K
